1. Field of The Invention
Embodiments of the present invention relate to an augmented reality display system.
2. Background
The function of an augmented reality (AR) display system is to overlay imagery on the user's view of the environment. There are a variety of hardware configurations in use or proposed for such a system. Quite often, the AR system is head-mounted, the user required to wear a helmet or some form of glasses. One of the challenges in designing a glasses-type AR display system is to make the hardware both physically light and compact. At the same time, the system must not overly intrude into the user's view of the environment. During the past few years, perhaps the highest profile example of such a system is the “Google Glasses.”
One common approach to the design of a glasses-type AR system uses a projector to produce the image. The projected image must then be directed to the user's eye. There are a variety of approaches by which this could be accomplished. An approach to redirecting the image used in several products or otherwise reported in the literature makes use of a full or semi-transparent mirror on the surface of at least one lens of the glasses.
There are several problems with this approach. The first is that a mirror fully blocks the user's view of the environment behind the mirror. Although somewhat of an improvement, a semi-transparent mirror will also significantly alter the user's view of the environment when looking through the semi-transparent mirror.
Perhaps of greater consequence is the fact that the mirror must be properly oriented and shaped to correctly reflect a focused image to the user's eye. It follows that, since the mirror is on the surface of the lens, the orientation and shape of the corresponding lens surface is dictated by the requirements of the mirror. This is illustrated in FIG. 1.
The “distortion” in the shape of the lens can, in turn, result in an AR system that causes a very undesired region of distortion in the user's view of the environment.
The invention described in this disclosure consists of a combination of device configurations and associated reflector material. The use of the invention is in a glasses-type AR system and serves the purpose of redirecting the projected image to the eye of the user. It does so in a way that is at least equivalent in weight and compactness to approaches, but is less obtrusive.